// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef BASE_BIG_ENDIAN_H_
#define BASE_BIG_ENDIAN_H_

#include <stddef.h>
#include <stdint.h>

namespace base {
    
// Read an integer (signed or unsigned) from |buf| in Big Endian order.
// Note: this loop is unrolled with -O1 and above.
// NOTE(szym): glibc dns-canon.c and SpdyFrameReader use
// ntohs(*(uint16_t*)ptr) which is potentially unaligned.
// This would cause SIGBUS on ARMv5 or earlier and ARMv6-M.
template<typename T>
inline void ReadBigEndian(const char buf[], T* out) {
    *out = buf[0];
    for (size_t i = 1; i < sizeof(T); ++i) {
        *out <<= 8;
        // Must cast to uint8_t to avoid clobbering by sign extension.
        *out |= static_cast<uint8_t>(buf[i]);
    }
}

// Write an integer (signed or unsigned) |val| to |buf| in Big Endian order.
// Note: this loop is unrolled with -O1 and above.
template<typename T>
inline void WriteBigEndian(char buf[], T val) {
    for (size_t i = 0; i < sizeof(T); ++i) {
        buf[sizeof(T)-i-1] = static_cast<char>(val & 0xFF);
        val >>= 8;
    }
}

// Specializations to make clang happy about the (dead code) shifts above.
template <>
inline void ReadBigEndian<uint8_t>(const char buf[], uint8_t* out) {
    *out = buf[0];
}

template <>
inline void WriteBigEndian<uint8_t>(char buf[], uint8_t val) {
    buf[0] = static_cast<char>(val);
}
    
//    // Allows reading integers in network order (big endian) while iterating over
//    // an underlying buffer. All the reading functions advance the internal pointer.
//    class BASE_EXPORT BigEndianReader {
//    public:
//        BigEndianReader(const char* buf, size_t len);
//        
//        const char* ptr() const { return ptr_; }
//        int remaining() const { return end_ - ptr_; }
//        
//        bool Skip(size_t len);
//        bool ReadBytes(void* out, size_t len);
//        // Creates a StringPiece in |out| that points to the underlying buffer.
//        bool ReadPiece(base::StringPiece* out, size_t len);
//        bool ReadU8(uint8_t* value);
//        bool ReadU16(uint16_t* value);
//        bool ReadU32(uint32_t* value);
//        bool ReadU64(uint64_t* value);
//        
//    private:
//        // Hidden to promote type safety.
//        template<typename T>
//        bool Read(T* v);
//        
//        const char* ptr_;
//        const char* end_;
//    };
//    
//    // Allows writing integers in network order (big endian) while iterating over
//    // an underlying buffer. All the writing functions advance the internal pointer.
//    class BASE_EXPORT BigEndianWriter {
//    public:
//        BigEndianWriter(char* buf, size_t len);
//        
//        char* ptr() const { return ptr_; }
//        int remaining() const { return end_ - ptr_; }
//        
//        bool Skip(size_t len);
//        bool WriteBytes(const void* buf, size_t len);
//        bool WriteU8(uint8_t value);
//        bool WriteU16(uint16_t value);
//        bool WriteU32(uint32_t value);
//        bool WriteU64(uint64_t value);
//        
//    private:
//        // Hidden to promote type safety.
//        template<typename T>
//        bool Write(T v);
//        
//        char* ptr_;
//        char* end_;
//    };
    
}  // namespace base

#endif  // BASE_BIG_ENDIAN_H_